Apparatus and method for freeing drafting rolls of adhering fibers

ABSTRACT

In an open end textile spinning apparatus having an electrostatic field established between fiber feed rolls and a fiber spinning head by which fiber is attracted from the fiber feed rolls towards the spinning head, the improvement comprising an alternating current source having a predetermined frequency operatively connected to one of the fiber feed rolls to effect rapid oscillation of the electrostatic field and electrical vibration of fibers adhering to the fiber feed rolls. If desired, a d.c. source can be added to the a.c. source to bias the electrostatic field potential lines of force closer to the roll surfaces. A method of using the apparatus comprises establishing an electrostatic field between the fiber feed rolls, which serve as a first electrode, and a fiber spinning head, which serves as a second electrode, and simultaneously applying an alternating current of predetermined frequency to at least one of the rolls. This causes the electrostatic field to oscillate between the rolls, which field oscillation electrically vibrates fiber adhering to the rolls. In addition, the positive a.c. potential cycle causes the fibers clinging to the cot, or upper delivery roll, to be repelled from it. When the a.c. potential cycle reverses, the fibers clinging to the lower delivery roll are attracted towards the cot roll. Once free of the roll surfaces, the fibers are drawn into the electrostatic field.

United States Patent 1 Tannas, Jr. et al.

1 APPARATUS AND METHOD FOR FREEING DRAFTING ROLLS OF ADHERING FIBERS [75] Inventors: Lawrence E. Tannas, Jr., Orange;

Paul K. York, Fullerton, both of Calif.

[73] Assignee: Electrospin Corporation, Columbus,

Ohio

[22] Filed: Apr. 19, 1971 [21] Appl. N0.: 135,313

[52] US. Cl. 57/56, 57/58.9l

[51] Int. Cl. D0lh 11/00, D0lh H12 [58] Field of Search 57/34 R, 34.5, 56, 57/58, 89, 58.91, 58.93, 58.95, 156

[56] References Cited UNITED STATES PATENTS 3,411,284 1l/1968 Corbaz et al. 57/58.91

3,107,478 10/1963 Arshinov et al. 57/156 X 2,711,626 6/1955 Oglesby, Jr. et al. 57/34 R [57] ABSTRACT In an open end textile spinning apparatus having an electrostatic field established between fiber feed rolls and a fiber spinning head by which fiber is attracted from the fiber feed rolls towards the spinning head, the improvement comprising an alternating current source having a predetermined frequency operatively connected to one of the fiber feed rolls to effect rapid oscillation of the electrostatic field and electrical vibration of fibers adhering to the fiber feed rolls. if desired, a dc. source can be added to the a.c. source to bias the electrostatic field potential lines of force closer to the roll surfaces.

A method of using the apparatus comprises establishing an electrostatic field between the fiber feed rolls, which serve as a first electrode, and a fiber spinning head, which serves as a second electrode, and simultaneously applying an alternating current of predetermined frequency to at least one of the rolls. This causes the electrostatic field to oscillate between the rolls, which field oscillation electrically vibrates fiber adhering to the rolls. In addition, the positive a.c. potential cycle causes the fibers clinging to the cot, or upper delivery roll, to be repelled from it. When the a.c. potential cycle reverses, the fibers clinging to the lower delivery roll are attracted towards the cot roll. Once free of the roll surfaces, the fibers are drawn into the electrostatic field.

9 Claims, 1 Drawing Figure APPARATUS AND METHOD FOR FREEING DRAFTING ROLLS OF ADHERING FIBERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to novel improvements in the electrical circuitry used with open end electrostatic spinning apparatus. In electrostatic spinning devices, an electrostatic field extends across an air gap or transport zone between the drafting system, which mechanically feeds discrete fibers into the field, and a spinning head which collects and twists or spins the fibers into yarn. The fibers typically are supplied to the drafting system in the form of roving or sliver and advantageously are discharged from the drafting system as a stream of discrete fibers into the electrostatic field, which field is effective to align the fibers and move them across the air gap to the spinning head. In operation, the fibers entering the electrostatic field are given an electrical charge by a first electrode, which conveniently may be the drafting rolls that discharge the fibers into the transport zone. Once delivered in a charged condition to the transport zone, most fibers follow the normal path of flow into a yarn gripper located within the spinning head. Attraction to the spinning head results from the second electrode, which is charged oppositely to the first electrode and which normally is located as a functional part of the spinning head.

Unfortunately, some of the fibers tend to adhere to the drafting rolls due to image forces caused by their charged condition and/or forces of mechanical adhesion. Such fibers accumulate and interfere with proper functioning of the spinning apparatus unless removed. The drafting rolls comprise a conductive delivery roll and an insulated cot roll. Periodically, it has been the practice to physically remove accumulated lapping fiber from the drafting rolls, but this is expensive, inconvenient and wasteful of fiber.

It is an object of this invention to provide an electrical system by which the electrostatic field between the feed roll and the cot roll, will be caused to vary or oscillate, which field oscillation will electrically vibrate fiber adhering to the roll surfaces.

It is a further object of this invention to provide a method of freeing the fiber feed surface of said drafting rolls from adhering fiber by electrically vibrating the adhering fibers.

These and other objects of .this invention will become more fully apparent by reference to the appended claims and to the following detailed description.

2. Summary of the Invention In an open end textile spinning apparatus having an electrostatic field established between fiber feed rolls and a fiber spinning head by which fiber is attracted by the fiber feed rolls towards the spinning head, the improvement comprising an alternating current source operatively connected to one of the fiber feed rolls to effect rapid oscillation (i.e. variation) of the electrostatic field and, thus, vibration of fibers adhering to the fiber feed rolls. If desired, a d.c. source can be added to the a.c. source to bias the electrostatic field potential lines of force closer to the roll surfaces.

A method of using the above apparatus comprises establishing an electrostatic field between the fiber feed rolls and a fiber spinning head and applying an alternating current to one of the rolls which causes the electrostatic field between the rolls to oscillate, which field oscillation vibrates fiber adhering to the rolls. In addition, one portion of the a.c. signal (eg the positive a.c. signal cycle portion) causes the fibers clinging to the cot roll to be repelled from it. When the a.c. signal cycle reverses, the fibers clinging to the delivery feed roll are attracted towards the cot roll. Once free of the roll surfaces as a result of vibration, the fibers are drawn into the electrostatic field.

DESCRIPTION OF THE DRAWING Other features of the invention will become apparent from the following more detailed description and from the accompanying drawing, in which the FIGURE is a partially schematic longitudinal section of a portion of an electrostatic open end spinning apparatus showing an alternating current source with an optional direct current source being applied thereto to provide a biased potential at the conductive axle of a cot roll.

DESCRIPTION OF THE PREFERRED EMBODIMENT The spinning apparatus shown embodies a drafting system 10. This drafting system comprises a pair of power driven inlet drafting rolls 11 and 12 between which roving or sliver is fed. A pair of power driven intermediate drafting belts l3 and 14 are entrained respectively about drive rolls l5 and 16 and nose bars 17 and 18 and an-idler roll 18a which guide and position the belt 13 and 14 so as to direct the fibers being advanced therebetween to a pair of fiber discharge drafting rolls in the form of fiber delivery roll 19 and cot roll 20. The draft of system 10 is sufficiently high that the discharge from rolls 19 and 20 is a stream of discrete fibers. Drafting roll 19 is fabricated of an electrically conductive material, such as metal, and is connected to a suitable reference potential, for example ground as indicated. Roll 19 serves as a drive roll for cot roll 20. Cot roll 20 has a fiber advancing surface in the form of outer dielectric sleeve 20b which is in rolling contact with roll 19 as shown. Dielectric sleeve 20b is mounted for rotation with respect to a fixed roller support shaft 20a which is mounted by insulated spring-biased arms (not shown) which biases the cot roll towards drive roll 19. Shaft 20a is fabricated of conductor material and, in prior devices, it was connected to the reference potential, e.g. ground. However, in this invention shaft 20a is connected to a.c. signal source 46 which is referenced to ground potential. A suitable d.c. bias source 48 may be connected to a.c. source 46 to control and establish a base-line potential for the a.c. signal produced by source 46.

Assembly 21 includes a normally stationary body 22' and end caps 23 and 23a mounted respectively on the upper and lower ends of the body22.

A twisting device in the form of spindle 24 acts as a spinning means which is journaled in the body 22 by axially spaced aligned anti-friction bearings 25 and 26 fixed within the central throughbore 27 of the body 22. Body 22 has a laterally extending side opening 28 to the enlarged central portion 29 of the spindle 24 which is frictionally driven by an endless belt 30 extending through opening 28 and continuously rotated by a drive portion of the spinning apparatus (not shown). While this is the preferred form, other electrostatically charged spinning means could also be employed.

Spindle 24 has an axial throughbore 31, the lower end of which defines a yarn discharge opening 32 from which spun yarn (not shown) is drawn by take-up or drawing rolls 33 and 34. I

The upper end of the spindle is counterbored at 35 to receive a gripper 36 in which fibers (not shown) are directed to be twisted and spun into yarn. Gripper 36 may, for example, be one of the types illustrated in U.S. Pat. No. 3,372,537, issued Mar. 12, 1968 to M. Poull et al. for Radially Clamping Grips.

The upper end of the spindle 24 has an extension 37 defining a conical fiber inlet opening 39. This extension is made of a dielectric material and is positioned for rotation within a centrally disposed through opening 38 in the cap 23.

The fiber receiving end of extension 37 has a funnelshaped aperture 39 terminating in a cylindrical opening 39a in axial alignment with and substantially equal in diameter to the inlet end of the gripper 36. A yarn tail extends through opening 39a from gripper 36 into the aperture 39 and fibers from rolls l9 and are assembled on the yarn tail as it rotates in the field.

The annular metallic electrode 40 of the electrostatic system is fixed within the body 22 of the spinning head 21 in axially aligned surrounding relation to the spindle 24 below the cap 23. Electrode 40 is connected by conductor 41 to a terminal of a high voltagepower supply, the other terminal of which is grounded. The upper external surface of electrode 40 is a segment of a sphere to provide satisfactory electrostatic field focusing.

The configuration of the electrostatic field is represented by dotted lines 42 as it extends from the outer dielectric surface of the cap 23 to the metallic portions of the rolls 19 and 20 that provide the ground for the electrostatic field. Cap 23 is annular, coaxial with spindle 24 and has an external surface which is a segment of a sphere substantially concentric with the center of the spherical surface of the electrode 40 so that its exposed dielectric surface is approximately normal to the field lines.

In operation, fibers entering the electrostatic field are given a charge by passing over the rotating fiber feeding surfaces of cot roll 20 and fiber delivery roll 19. A small portion of these fibers adhere to the cot roll 20. These may be removed as accumulated waste or they may adhere and aggravate further lapping. In either case they represent a hazard to process continuity and must eventually be removed, or else the waste material may result in machine downtime. However, source 46 produces an alternating current signal which is applied to the cot roll shaft 20a (which is a conductor) thereby causing the charged fibers adhering to the cot roll to be driven away (i.e. electrostatically repelled from the cot roll) as the signal on the shaft goes positive, assuming that the cot roll is being used as the positive electrode.

Since the fibers are charged electrostatically as they emerge from the drafting unit, they can be or vibrated oscillated by applying an alternating current signal having a desired frequency to the cot shaft 20a. Obviously any desired frequency can be selected, although it has been found thatfor most fibers a frequency within the range of from I to 600 Hz is effective. The alternating current signal causes adhering fibers to vibrate in a generally transverse manner to the downward direction in response to the shifting electrostatic field, thereby loosening the fibers from any entanglement with each other or from adhesion to the drafting rolls. A fundamental purpose in an electrical sense of applying an alternating current on the cot shaft is to counteract the image and [or adhesive forces which are holding the fibers to the surfaces of the cot and delivery rolls whereby these fibers are released from the cot roll. A fiber on the cot roll, when released, drops into the region between the electrodes and is accelerated toward the spinning head. The electric field between the electrodes is so intense that once a fiber has moved a small distance from the cot roll surface, it will not be attracted back to the surface. As a safety measure, a current-limiting resistor 44 is placed in series between shaft 20a and the voltage sources 46 and 48.

A direct current voltage source 48 is connected in series with alternating current source 46 so that a direct current bias potential can be added to the alternating current potential. The effect of applying d.c. voltage in this manner is to bend the electrostatic field lines of force nearer to the drafting roll surfaces. The electrostatic field still shifts between delivery roll 19 and cot roll 20b. A battery has been shown as the voltage source 48 but other sources of direct current could also be employed. In the preferred form a large alternating current voltage is used with a small direct current voltage, as for example, an alternating current voltage of 1,000 volts having a frequency of 400 cycles per second in series with a direct current voltage of 50 volts.

An electrostatic field line of force 42a shown near the cot roll surface is representative of the position of a field line of force when the cot axle potential is negative. Upon the alternating current potential going positive, field line of force 42a shifts downwardly away from the cot roll surface to the position shown by line 42b. A fiber clinging to the cot roll would have been repelled away from the positive cot roll and have been captured by the intense electrostatic field.

When the cot axle potential is negative, a positively charged fiber clinging to the delivery roll 19 is attracted towards the cot roll. Rapid oscillation of the electrostatic field, as for example at 400 cycles per second, causes a fiber having a portion adhering to one of the drafting rolls to vibrate a portion not adhering on the roll surface towards and away from the roll surface. This vibration loosens the mechanical forces of adhesion while electrical forces are causing repulsion of fiber at the cot roll and attraction of fiber on the delivery roll towards the cot roll.

Other vibration inducing mechanisms, such as, for example, a mechanical transducer, could be employed in place of the alternating current voltage source to vibrate fiber lapping the draft rolls. However, the alternating current form is preferred in that it can additionally be used to gain the added advantage of rapid oscillation of the electrostatic field.

Thus, in a mechanical sense, a stronger resulting force vibrates the lapping fibers to free them of adhesion or entanglement on the drafting rolls.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

We claim:

in an open end textile spinning apparatus having an electrostatic field established between fiber feed means and a fiber spinning means by which fiber is attracted from said fiber feed means towards said spinning means, the improvement comprising:

circuit means connected to at least one of said fiber feed means and said fiber spinning means,

said circuit means producing a signal which causes periodic variations in said electrostatic field in order to cause vibration of fiber adhering to said fiber feed means, whereby said fiber feed means is freed of adhering fiber.

2. The invention as defined in claim 1 wherein said circuit means comprises a voltage source generating an alternating current signal, and means connecting said voltage source wijh said fiber feed means.

3. The invention as defined in claim 2 wherein said fiber feed means is a pair of drafting rolls, one of said rolls being driven about a stationary axle by the other of said rolls.

4. The invention as defined in claim 3 wherein said one roll has a dielectric surface and said stationary axle is connected to said circuit means.

5. The invention as defined in claim 2 wherein said circuit means further includes a direct current voltage source applied to said alternating current voltage source to bias said electrostatic field.

6. In an open end textile spinning process using an electrostatic field to transport fiber from fiber feed means to fiber spinning means, the method of freeing said fiber feed means of adhering fiber comprising:

establishing an electrostatic field between said fiber feed means and said fiber spinning means; and

applying an alternating current signal to said fiber feed means to effect oscillation of said electrostatic field and vibration of fiber adhering to said fiber feed means.

7. The method as defined in claim 6 further comprising using a pair of drafting rolls, one of which rolls is mounted on a conductive axle and has a dielectric surface as the fiber feed means, and applying said altemating current to said conductive axle.

8. The method as defined in claim 6 further comprising biasing said electrostatic field by applying a direct current to said fiber feed means.

9. Apparatus for spinning textile fibers, comprising:

a. fiber feed means having a distribution end;

b. fiber twisting means spaced from said feed means and having an axial inlet generally directed toward said discharge end of said feed means for receiving fibers discharged by said feed means; and

c. a variable electrical field produced by a variable voltage source having a first electrode connected to said fiber feed means to produce an electric charge on said fibers while passing through said feed means whereby said fibers are vibrated by said variable electrical field such that the fibers do not adhere to said feed means and upon said fibers being discharged from said feed means said electrical field between said feed means and said axial inlet exerts a pulling force on said fibers simultaneously straightening and aligning the fibers with the axial inlet and causing said fibers to move across the space between said feed means and said axial inlet where the straightened aligned fibers are twisted into thread by said twisting means.

Dedication 3,74:4:,231.Lawence E. Tom'nas, J12, Orange, and Paul K. Y 0146, Fullerton,

Calif. APPARATUS AND METHOD FOR FREEING DRAFT- ING ROLLS OF ADHERING FIBERS. Patent dated July 10, 1973. Dedication filed Mar. 23, 1977, by the assignee, Electrospin Uwpomtion.

Hereby dedicates t0 the Public the entire term of said patent.

[Ofiioial Gazette May 10, 1.977.] 

1. In an open end textile spinning apparatus having an electrostatic field established between fiber feed means and a fiber spinning means by which fiber is attracted from said fiber feed means towards said spinning means, the improvement comprising: circuit means connected to at least one of said fiber feed means and said fiber spinning means, said circuit means producing a signal which causes periodic variations in said electrostatic field in order to cause vibration of fiber adhering to said fiber feed means, whereby said fiber feed means is freed of adhering fiber.
 2. The invention as defined in claim 1 wherein said circuit means comprises a voltage source generating an alternating current signal, and means connecting said voltage source wijh said fiber feed means.
 3. The invention as defined in claim 2 wherein said fiber feed means is a pair of drafting rolls, one of said rolls being driven about a stationary axle by the other of said rolls.
 4. The invention as defined in claim 3 wherein said one roll has a dielectric surface and said stationary axle is connected to said circuit means.
 5. The invention as defined in claim 2 wherein said circuit means further includes a direct current voltage source applied to said alternating current voltage source to bias said electrostatic field.
 6. In an open end textile spinning process using an electrostatic field to transport fiber from fiber feed means to fiber spinning means, the method of freeing said fiber feed means of adhering fiber comprising: establishing an electrostatic field between said fiber feed means and said fiber spinning means; and applying an alternating current signal to said fiber feed means to effect oscillation of said electrostatic field and vibration of fiber adhering to said fiber feed means.
 7. The method as defined in claim 6 further comprising using a pair of drafting rolls, one of which rolls is mounted on a conductive axle and has a dielectric surface as the fiber feed means, and applying said alternating current to said conductive axle.
 8. The method as defined in claim 6 further comprising biasing said electrostatic field by applying a direct current to said fiber feed means.
 9. Apparatus for spinning textile fibers, comprising: a. fiber feed means having a distribution end; b. fiber twisting means spaced from said feed means and having an axial inlet generally directed toward said discharge end of said feed means for receiving fibers discharged by said feed means; and c. a variable electrical field produced by a variable voltage source having a first electrode connected to said fiber feed means to produce an electric charge on said fibers while passing through said feed means whereby said fibers are vibrated by said variable electrical field such that the fibers do not adhere to said feed means and upon said fibers being discharged from said feed means said electrical field between said feed means and said axial inlet exerts a pulling force on said fibers simultaneously straightening and aligning the fibers with the axial inlet and causing said fibers to move across the space between said feed means and said axial inlet where the straightened aligned fibers are twisted into thread by said twisting means. 